Microporous materials, including zeolites and silicoaluminophosphates, are widely used in the petroleum industry as absorbents, catalysts and catalyst supports. Their crystalline structures consist of three-dimensional frameworks containing uniform pore openings, channels and internal cages of dimensions (<20 Å) similar to most hydrocarbons. The microporous structures of these materials allow them to absorb molecules whose size is equal to or less than the size of the pore openings. The composition of the frameworks can be such that they are anionic, which requires the presence of non-framework cations to balance the negative charge. These non-framework cations, such as alkali or alkaline earth metal cations, are exchangeable, either entirely or partially with another type of cation utilizing ion exchange techniques in a conventional manner. If these non-framework cations are converted to the proton form by, for example, acid treatments or exchange with ammonium cations followed by calcination to remove the ammonia, it imparts the material with acid sites having catalytic activity. The combination of acidity and restricted pore openings gives these materials catalytic properties unavailable with other materials due to their ability to exclude or restrict some of the products, reactants, and/or transition states in many reactions. Non-reactive materials, such as pure silica and aluminophosphate frameworks are also useful and can be used in absorption and separation processes of liquids, gases, and reactive molecules such as alkenes.
The family of crystalline microporous compositions known as zeolites exists as mineral and synthetic species. Their microporous frameworks contain tetravalent silicon tetrahedra atoms connected by bridging oxygen atoms. It is possible that some or all of the silicon atoms can be substituted with other tetravalent atoms capable of tetrahedral coordination, such as germanium, titanium, or zirconium. Some of the tetrahedral atoms can also be replaced with trivalent metal atoms such as aluminum, gallium, and/or iron to form an anionic framework as described above. U.S. Pat. No. 6,471,941 discloses one such microporous zeolite composition designated ITQ-13, which has a three-dimensional framework of channels containing 9, 10, and 10 tetrahedral atoms in the pore openings along the three crystallographic directions.
Another family of crystalline microporous compositions known as molecular sieves, which exhibit the ion-exchange and/or adsorption characteristics of zeolites is the aluminophosphates, identified by the acronym AlPO, and substituted aluminophosphates as disclosed in U.S. Pat. Nos. 4,310,440 and 4,440,871. U.S. Pat. No. 4,440,871 discloses a class of silica aluminophosphates, which are identified by the acronym SAPO and which have different structures as identified by their X-ray diffraction pattern. The structures are identified by a numerical number after AlPO, SAPO, MeAPO (Me=metal), etc. (Flanigen et al., Proc. 7 th Int. Zeolite Conf., p. 103 (1986) and may include Al and P substitutions by B, Si, Be, Mg, Ge, Zn, Fe, Co, Ni, etc.
ExxonMobil and others extensively use various microporous materials, such as faujasite, mordenite, and ZSM-5 in many commercial applications. Such applications include reforming, cracking, hydrocracking, alkylation, oligomerization, dewaxing and isomerization. Any new material has the potential to improve the catalytic performance over those catalysts presently employed.
There are currently over 160 known microporous framework structures as tabulated by the International Zeolite Association. There exists the need for new structures, having different properties than those of known materials, for improving the performance of many hydrocarbon processes. Each structure has unique pore, channel and cage dimensions, which gives its particular properties as described above. ITQ-34 is a a new molecular sieve having a unique framework structure.